1. Field of the Invention
The invention relates to a method for cutting media from a multi-roll printing system, a cutting assembly for a multi-roll printing system, and a multi-roll printing system.
2. Description of Background Art
A multi-roll or tandem roll printing system comprises a plurality of media rolls provided on a common roll support axis. When driving the roll support axis, the media rolls rotate at the same rotational speed. The media supplied from the media rolls are then advanced in a synchronous motion across a transport path of the printing system towards an inkjet printing assembly, which swath-wise prints a respective image on each of the media. Downstream of the inkjet printing assembly a cutting device is provided for cutting the regions of the media comprising the printed images from the remainder of each of the respective media. The cutting device is generally a knife provided on a guide rail extending across the full width of the transport path for the media. The knife simultaneously cuts all the media output by the multi-roll printer in a single stroke. However, when the printing of a first image on a first medium is completed before the printing of a second, for example longer, image on a second medium, cutting cannot be performed before completion of printing the second image to avoid cutting into the second image. Cutting is performed after completion of the second image. Since the media move in tandem, a section of the first medium will be unprinted and will, after simultaneous cutting, be attached to the region with the first image. This unprinted section is then removed in a separate (and a generally manual) cutting operation. For certain print jobs, the costs of media are very high, for example several hundreds of dollars or euros per meter. As the unprinted section is discarded, thereby wasting precious material. Thereby, the material and operational costs for such a multi-roll printing system are relatively high.
In another multi-roll printing system according to the prior art, the knife is controlled to move along the guide rail over a distance corresponding to the width of the medium being cut. During transport of the media, the knife is positioned in between two media. Drawback of said prior printing system is the risk of damage to media. When the knife is not accurately controlled, it cuts into the medium adjacent the medium being cut, for example due to overshoot. Further drawback is that the knife may only cut adjacent media. When three or more separate media are output in parallel, configurations arise wherein the knife is separated from the to be cut medium by another medium, preventing the knife from cutting the desired medium. Operation of such a printing system becomes relatively complex when using higher numbers of media.